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Hydronephrosis is the buildup of urine in the kidney that can be caused by a blockage (e.g., kidney stone, tumor) or congenital defect, usually at the ureteral pelvic junction, that does not allow urine to flow properly into the bladder and subsequently exit the body. Hydronephrosis in the setting of obstruction can occur uni- or bilaterally, and if not diagnosed and treated accordingly can cause varying degrees of permanent renal dysfunction. At UPMC Children’s, pyeloplasty is the corrective surgical approach to most cases of ureteropelvic junction obstruction. The procedure can be done in an open manner, or through a minimally invasive robotic-assisted surgery (pyeloplasty is one of the top uses of robotic-assisted urologic surgery at UPMC Children’s).
UE is a relatively modern advance in the field of ultrasound imaging, one that allows for the noninvasive measurement of organ or vessel elasticity to aid in the diagnosis and assessment of disease states. Conversely, the imaging technology can detect levels of fibrosis in organs such as the liver or kidneys and lesions in the breast, and it can aid prostate biopsies, among other uses. Dr. Chaudhry’s pilot study of hydronephrosis using UE was conceived over the last several years in collaboration with Judy Hereford Squires, MD, director of Pediatric Ultrasound Imaging and assistant director of Radiology Residency Programs in the Department of Radiology at UPMC Children’s. The pilot study began enrolling patients in fall 2019; 10 to 15 patients are the target goal for enrollment in the pilot study.
At its root, Dr. Chaudhry’s study is designed to see if UE can be a sensitive and specific (and noninvasive) imaging modality for diagnosing and monitoring hydronephrosis, particularly in very young children who are under the age of 2.
“Hydronephrosis, blockages, and kidney function can sometimes be difficult to assess, and even more so in the very young, primarily due to their still-developing kidneys. The standard that we have now is the mercapto-acetyltriglycine-3 (MAG 3) Lasix renal scan, which is a nuclear medicine study. While we can determine several pieces of information from this study, it requires an IV, is time consuming, expensive, and requires small doses of radiation. It is not a diagnostic procedure that you can or would want to do every three months in an infant if you are monitoring a patient’s renal and urine function to determine if surgery is needed, and identify when to avoid permanent loss in kidney function,” says Dr. Chaudhry.
The MAG 3 Lasix renal scan provides essentially two pieces of information to clinicians. The first is that it can determine if a kidney is obstructed by tracking the time it takes for the radiotracer to be excreted by the kidney. The second piece of information that the scan can reveal is a measurement of renal function in the obstructed kidney relative to the unobstructed kidney. The combination of these two readings can lead to a diagnosis of an obstruction for which surgical intervention may be required.
However, MAG 3 Lasix renal scans are not as accurate in children (under the age of 2) and neonates, specifically in those under the age of 3 months. Therefore, is there another imaging modality that can improve upon the accuracy of diagnosis for these young patients, and do so in a less invasive manner? One that can be performed routinely in the clinic or the radiology lab?
The study is designed to compare the effectiveness of UE versus MAG 3 scans, with each patient receiving two to three sequential UE scans while they are being monitored for obstruction and hydronephrosis in addition to a MAG 3 scan.
“We will compare the two studies to see if UE correlates with the MAG 3 findings over time and whether it helps us predict the progression and time to pyeloplasty,” says Dr. Chaudhry. “Diagnosing some of these obstructions and cases of hydronephrosis can be tricky. We do not want to do surgery if it is not warranted, particularly on very young neonates, if it appears as though their function is not impaired or is improving.
However, we also do not want to wait too long and risk permanent renal injury if surgery is warranted. With the ultrasound, we can take readings virtually anytime the patient is in the clinic — monthly, for example — and very closely monitor their status.”
Time will tell if UE is a viable monitoring methodology for these hydronephrosis patients; if the pilot results are promising, Dr. Chaudhry and his collaborators will seek to expand their study into a larger trial with more power to show efficacy.
Avoiding renal injury in these cases takes on special significance. Because many of these patients are so young, any permanent kidney damage sustained may be a life-long issue with potentially life-altering consequences. Having a noninvasive, cost-effective, repeatable monitoring framework and algorithm in place should UE ultimately prove efficacious would be a practice-changing development for pediatric urologists.
Rajeev Chaudhry, MD, is an assistant professor of urology in the Department of Urology at the University of Pittsburgh School of Medicine and a pediatric urologist in the Division of Pediatric Urology at UPMC Children’s. Dr. Chaudhry earned his medical degree from the Warren Alpert Medical School of Brown University. Dr. Chaudhry completed a residency in urology and a urology research fellowship at Duke University Medical Center in Durham, North Carolina. He then completed a fellowship in pediatric urology at UPMC Children’s prior to joining the Division as a faculty member. Dr. Chaudhry’s research interests include the application of bioengineering and robotics in surgery, disorders of sexual differentiation, and neurogenic bladder. His clinical interests include pediatric robotic surgery and complex reconstruction in patients with spina bifida.